Alana Arnold, PharmD
• Define bronchiolitis
• Describe etiology and prevalence
• Define clinical manifestations
• Describe pathophysiology
• Describe diagnosis and treatment
• Identify strategy for prevention
Bronchiolitis is an acute inflammation
of the bronchioles (smaller airways
that branch off the main airway) and
is usually caused by a viral infection
that occurs primarily in young infants,
most often in those aged 2-24
The virus is transmitted from person-to-person by direct contact with
nasal secretions or by airborne droplets.
– Respiratory syncytial virus: (85% during winter months)
– Parainfluenza (25%)
– Adenovirus (5%)
Other less common etiologic agents include the following:
– Mycoplasma pneumoniae (5%)
– Enterovirus (5%)
– Influenza virus (5%)
– Rhinovirus (5%)
RSV generally causes only mild symptoms in adults but can result in severe
illness in infants often requiring hospitalization.
In the US:
11.4% in children younger than 1 year
6% in those aged 1-2 years
= 17 % infant hospitalization
Usually affects children under the age of 2, with a peak age of 3 to 6 months.
Bronchiolitis occurs as many as 1.5 times more frequently in males.
The frequency in developed countries appears to be similar to that in the US.
Peak incidence usually occurs during winter months in temperate climates and
during the rainy season in tropical climates.
Shay DK, Holman RC, Newman RD: Bronchiolitis-associated hospitalizations among US children, 1980-1996. JAMA 1999 Oct 20;
Age (< 6 months old)
No history of being breastfed
– (born before 37 weeks gestation)
Exposure to cigarette smoke
Crowded living conditions
Bronchiolitis begins as a mild upper respiratory infection that,
over a period of 2 to 3 days, can develop into a condition of
increasing respiratory distress with wheezing and a
"tight" wheezy cough. The infant's breathing rate may
increase markedly (tachypnea), and the infant may become
irritable or anxious looking. If the disease is severe
enough, the infant may turn bluish (cyanotic) which is an
indication of a critical emergency.
As the effort of breathing increases, parents may see the
nostrils flaring with each breath and the muscles between
the ribs retracting as the child tries to inhale air. This can
be exhausting for the child, and very young infants may
simply fatigue to an extent that breathing becomes difficult to
Summary of Clinical Manifestations
– Cough, wheezing, shortness of breath
– Rapid breathing (tachypnea)
often at rates over 50-60 breaths per minute
– (most common physical sign)
– Intercostal retractions
– Nasal flaring in infants
– Fever (variable) usually in the range of 38.5-39°C
– Bluish skin due to lack of oxygen (cyanosis)
– Vomiting, especially post-tussive
– Poor feeding or anorexia
Infection of bronchiolar respiratory and ciliated
epithelial cells produces increased mucus secretion,
cell death, and sloughing, followed by a
peribronchiolar lymphocytic infiltrate and
Causes Narrowing and obstruction of small airways.
Resulting in decreased ventilation of portions of the
lung, resulting in hypoxia. Work of breathing is
increased due to increased end-expiratory lung
volume and decreased lung compliance.
Physical and Laboratory Findings
– Wheezing and crackling sounds are heard by
stethoscope examination of chest.
– Decreased blood oxygen levels
– Tests often include a chest X-ray and blood gases.
– Antigen tests of nasal washings provide rapid (usually
within 30 min) and accurate detection of RSV.
– A positive culture can confirm the diagnosis of RSV infection.
– Nasal washings should be obtained from children at risk for
– Respiratory viral panels, cultures for RSV or other viruses may
– CBC is seldom useful since the white blood cell (WBC)
count is usually within normal limits.
Other things to consider:
– Cystic Fibrosis
– Congestive Heart Failure
– IV fluids
Supportive therapy may also include chest clapping or postural
drainage to aid in secretion removal.
Antibiotics are NOT effective against viral infections. In extremely ill
children, antiviral medications (such as ribavirin) are sometimes used.
Taber LH, Knight V, Gilbert BE, et al: Ribavirin aerosol treatment of bronchiolitis associated with respiratory syncytial
virus infection in infants. Pediatrics 1983 Nov; 72(5): 613-8
Suggested guidelines for admission
– Oxygen saturation less than 94% after therapy.
– Respiratory distress (eg, respiratory rate >60/min or retractions at rest)
– Younger than 2 months or history of prematurity
– Underlying cardiopulmonary disease or immunosuppression
High-risk patients and patients with moderate respiratory distress
or persistent hypoxemia should be admitted for the following:
– Oxygen therapy and apnea monitoring
– Restoration and/or maintenance of fluid balance
Infants with a history of gestational age less than 34 weeks, infants
younger than 6 weeks, and infants with congenital or acquired
immunodeficiency are at high risk for severe RSV infection and
require heightened vigilance.
Beta-2 agonist relaxes bronchial smooth
The therapeutic use of bronchodilators remains
controversial because there is conflicting evidence in
regards to the efficacy of bronchodilators in
bronchiolitis, it is reasonable to administer albuterol
(0.15mg/kg/dose) on a trial basis to patients with
bronchiolitis and access the clinical response. If
improvement in retractions, respiratory rate and
wheezing is noted, scheduled aerosol treatments may
There is evidence for the use of epinephrine as a
bronchodilator for patients with bronchiolitis.
SC: 0.01 mL/kg of 1:1000 solution SC q15-20min,
not to exceed 0.3 mL
<2 years: 0.25 mL of 2.25% solution in 3 mL NS
>2 years: 0.5 mL of 2.25% solution in 3 mL NS
Anticholinergic bronchodilator acting at muscarinic
receptors of parasympathetic nervous system.
Inhibits smooth muscle contraction and is useful in
patients with a significant bronchospasmodic
component of the illness.
Has antisecretory properties and, when applied
locally, inhibits secretions from glands lining the
nasal mucosa. It is synergistic with beta2-agonists.
Dose Nebulizer: 250 mcg mixed with albuterol
solution q20min for 3 doses, then q2-4h prn
Schuh S, Johnson D, Canny G, et al: Efficacy of adding nebulized ipratropium bromide to nebulized albuterol
therapy in acute bronchiolitis. Pediatrics 1992 Dec; 90(6): 920-3
Despite the prominent role that inflammation plays in the
pathogenesis of airway obstruction, corticosteroid use remains
In a recent randomized, double-blind, placebo controlled trial in
children admitted to the hospital with RSV bronchiolitis, prednisolone
(1 mg/kg/day orally for 7 days) was thought to be effective in
accelerating the clinical recovery of these children (van Woensel).
A study by Klassen and colleagues was conducted to determine the
clinical benefit of oral dexamethasone in children admitted to
hospital with bronchiolitis treated with nebulized salbutamol. The
authors concluded that oral dexamethasone therapy does not affect
the clinical course of children hospitalized with bronchiolitis.
Currently, the evidence for the use of
glucocorticosteroids for children with
bronchiolitis is equivocal.
– Block release of inflammatory mediators by inhibition of
phospholipase and may be useful in patients with asthma
or in bronchiolitis with asthmatic qualities.
– 2 mg/kg PO initial, then 1 mg/kg/day in 1-2 daily doses;
not to exceed 60 mg/d for 3-10 days
– Hyperglycemia, edema, osteonecrosis, peptic ulcer
disease, hypokalemia, osteoporosis, euphoria, psychosis,
growth suppression, myopathy, and infections are possible
complications of glucocorticoid use
So what do ya do?
RSV is the most common viral
organism associated with severe
bronchiolitis and prevention in
high-risk patients is important!
– Indicated for the prevention of
serious lower respiratory tract
(LRT) disease in pediatric patients
at high risk of severe RSV disease,
such as infants with
bronchopulmonary dysplasia (BPD)
or a history of premature birth
(<35 weeks gestational age).
– Has been available since 1999
Humanized monoclonal antibody
Approved by the FDA for prevention of serious lower respiratory tract
disease in pediatric patients at high risk of RSV infection. If the
patient has already been infected with RSV this season and remains
at high risk, consider palivizumab prophylaxis for the remainder of
the season after resolution of the infection.
Dose: 15 mg/kg/dose IM monthly during the RSV season
(Nov - April)
Dosage Form: Palivizumab is supplied in a 50 and 100 mg vial and
should be reconstituted to a concentration of 100 mg/mL for
(cost per 100 mg = $960)
IMpact--RSV Study Group: Palivizumab, a humanized respiratory syncytial virus monoclonal antibody, reduces hospitalization from
respiratory syncytial virus infection in high-risk infants. Pediatrics 1998 Sep; 102(3 Pt 1): 531-7
Children’s Hospital Guidelines
Should be given in patients meeting one of the following criteria:
1. Less than 24 months and current ventilator or oxygen dependence for any reason
2. Less than 24 months with chronic lung disease (BPD or other severe CLD) AND
*on supplemental oxygen within the past 6 months or
*on diuretic therapy as a replacement for oxygen therapy
3. Less than 24 months with severe chronic disorders compromising lung function (CDH, chest wall
disorders, congenital lung malformation)
4. Gestational age 29-32 weeks and <6 months postnatal age at the start of RSV season or gestational age
<28 weeks and <12 months postnatal age at the onset of RSV season.
5. Less than 12 months with high risk congenital heart disease and meets criteria as established by the
Department of Cardiology
May be given in patients meeting one of the following criteria:
6. Gestational age 32-35 weeks if born < 6 months before the start of the RSV season and other risk factors
present which include the following; Multiple Birth, Young Siblings, Day-Care Attendance, exposure to
7. Less than 24 months at the onset of RSV season and severely immunocompromised (e.g. BMT,
lung, heart, liver, or renal transplant) AND
*is within a year of transplantation or
*is on high doses of immunosuppressive agents
Complications and Prognosis
– Secondary infection, such as pneumonia
– Respiratory failure.
– Airway disease, such as asthma that may occur later in life.
– The majority of children recover without sequelae. The course of disease
is usually 7-10 days.
– Bronchiolitis has been identified as a risk factor for asthma, but this does
not necessarily imply causation. The relationship between RSV infection
and later development of asthma is still not understood, but children who
have had bronchiolitis seem more likely to develop asthma than those
who have not.
– Children already predisposed to asthma may be more likely to wheeze
when they have RSV or other respiratory infectious stimuli.
Morbidity and Mortality
Morbidity: Significant morbidity is rare.
3% of cases
17% of all infant hospitalizations
3-7% Mechanical ventilation is required
– 1-2% of all hospitalized patients
– 3-4% for patients with underlying cardiac or pulmonary
– Majority of deaths occur in infants younger than 6 months.
– 4500 deaths per year